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Found a Sansui 9090db in a bulk collection pile need some help! :)

Check the fuses with a meter. Don't rely on appearance. If fuses are ok, check the voltages on the output transistors and on the driver board. Tape up the meter probe tip so only the very tip is exposed. This will help prevent shorting things out when you slip with the probe. If you had a scope I would say look at the inputs to the driver board and see if you have signal there. It is possible the problem is on the Dolby board because even with the Dolby off, the signal passes through the board multiple times. It's a horrible design.
 
The only thing I'd add is that, if this will be your first repair of vintage gear, DON'T DO IT! At least practice on something you pick up from Goodwill, etc. The 9090DB isn't a simple design and you MAY cause more harm than good. @onwardjames was right on in suggesting to take it to a tech, or find one here on AK that's actually worked on one. Believe me, I'm all for working on my own gear, but at least start simple before tackling this one.
 
dr*audio said:
Check the fuses with a meter. Don't rely on appearance. If fuses are ok, check the voltages on the output transistors and on the driver board. Tape up the meter probe tip so only the very tip is exposed. This will help prevent shorting things out when you slip with the probe. If you had a scope I would say look at the inputs to the driver board and see if you have signal there. It is possible the problem is on the Dolby board because even with the Dolby off, the signal passes through the board multiple times. It's a horrible design.
Click to expand...


Yeah so my father and I think the no sound issue is the output transistors and the fact that phono wouldn't play anything initially, that is the Dolby board. Do you know a price to fix this? There's a local guy here in SA that I am going to take it to.
 
jheu02 said:
The only thing I'd add is that, if this will be your first repair of vintage gear, DON'T DO IT! At least practice on something you pick up from Goodwill, etc. The 9090DB isn't a simple design and you MAY cause more harm than good. @onwardjames was right on in suggesting to take it to a tech, or find one here on AK that's actually worked on one. Believe me, I'm all for working on my own gear, but at least start simple before tackling this one.
Click to expand...

Yup, I watched a video of how the sound travels through the receiver and the Dolby board was a big oof. :crazy::rflmao:
 
erikharrison said:
... Do you know a price to fix this? There's a local guy here in SA that I am going to take it to.
Click to expand...

Tough question to answer, techs mostly charge by the hour for services rendered (labor) and then there is the cost for parts. What a Tech might charge for both in San Antonio could be totally different from say a tech in Buffalo or Seattle.

Take it in ask to have an assessment done before you commit to the process. There's nothing worse then dropping it or anything else for that matter and then getting a phone call several days/weeks later saying "it's fixed!" that'll be XXX dollars which could be more then you were willing to pay.
 
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erikharrison said:
Yup, I watched a video of how the sound travels through the receiver and the Dolby board was a big oof. :crazy::rflmao:
Click to expand...

While it is, to put it mildly, one monkeyfuck of a mess, it CAN be fixed.

@LBPete where are ya, good sir?? This is your kung fu, and it is strong.

Dswankey said:
Tough question to answer, techs mostly charge by the hour for services rendered (labor) and then there is the cost for parts. What a Tech might charge for both in San Antonio could be totally different from say a tech in Buffalo or Seattle.

Take it in ask to have an assessment done before you commit to the process. There's nothing worse then dropping it or anything else for that matter and then getting a phone call several days/weeks later saying "it's fixed!" that'll be XXX dollars which could be more then you were willing to pay.
Click to expand...

SOLID advice for those with a tight budget.

Me, I got mine overhauled by the legend, one Echowars. Glenn did this baby up right, and letting it go was difficult. I never heard another of the big vintage babies do what mine did. I got out of it about what I had in it, and this was way back in 2017 or so.

They command even more, now.

Best of luck, bud. Wishing you the best.
 
(If this post is out of line, please delete or I will delete.)
Whatever you do, don't send your unit to Crossed Paths Vintage,
in Burleson,Texas.
 
If the output transistors are blown, the fuses will be blown. If the fuses are not blown, the outputs should be ok since the relay clicks. The power transformer could have an open secondary which is why I told you to check the voltages.
Do not take this to just any tech. The tech needs to be very familiar with this model because of the Dolby board.
There are 60 feed thrus on the Dolby board that connect the traces on both sides of the board. They become intermittent. The board has to be removed, the selector switch has to be removed, and a wire inserted through each of the feed thrus, bent over on both sides of the board and soldered on both sides of the board. If it has green flex cable on the Dolby board, it needs to be replaced with ribbon cable. There are several other things that have to be done to this model to make it reliable and this is not a job for a guy who doesn't know the model. You can tell if he knows it because he will shudder or hang his head when he sees it. Or say, "Oh boy." and not in a happy way.
I'm being a bit over dramatic here, but it's not my favorite model to work on. I can make them sing but it's not a fun job.
Expect a bill of over $500 if it is done right. Many hours of work.
 
dr*audio said:
If the output transistors are blown, the fuses will be blown. If the fuses are not blown, the outputs should be ok since the relay clicks. The power transformer could have an open secondary which is why I told you to check the voltages.
Do not take this to just any tech. The tech needs to be very familiar with this model because of the Dolby board.
There are 60 feed thrus on the Dolby board that connect the traces on both sides of the board. They become intermittent. The board has to be removed, the selector switch has to be removed, and a wire inserted through each of the feed thrus, bent over on both sides of the board and soldered on both sides of the board. If it has green flex cable on the Dolby board, it needs to be replaced with ribbon cable. There are several other things that have to be done to this model to make it reliable and this is not a job for a guy who doesn't know the model. You can tell if he knows it because he will shudder or hang his head when he sees it. Or say, "Oh boy." and not in a happy way.
I'm being a bit over dramatic here, but it's not my favorite model to work on. I can make them sing but it's not a fun job.
Expect a bill of over $500 if it is done right. Many hours of work.
Click to expand...


Perfect reply, thank you.
 
The 9090db I worked on lost its channels in one of the big switches and flushing that nest of wafers and wires go it back to working. It did not have the dolby board issues.

If you haven't cleaned every switch and control with deoxit it is time to do so. If you are not comfortable with that, take it in.

Price between 85 the put it on the bench fee and about 1200 if it gets a full recap and the dolby board fully refurbished. Just fixing it, hard to tell, not knowing what is wrong as a lot could cause those issues.
 
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